Standing and fighting at Sharpsburg. Pickett's Charge. Each of these decisions could rightfully be labeled as Robert E. Lee's greatest mistake during his Civil War career. But one that often flies under the radar is the decision Lee made earlier in the Maryland Campaign to divide his army and send a large portion of it into the Shenandoah Valley to subdue the Federal garrisons positioned in Martinsburg and Harpers Ferry. A bold plan to be sure, this plan alone was not the undoing of Lee's campaign. Instead, it was the assumptions he made about how quickly his soldiers could open the Confederate supply line in the Shenandoah Valley.
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| Robert E. Lee |
Robert E. Lee was aware of the Union garrisons in the Valley before his men set foot on Maryland soil. But his crossings near Leesburg armed him with the belief that his intervention between those garrisons and Washington City and Baltimore would force the evacuations of Martinsburg and Harpers Ferry. It did not. Before Lee could advance his army farther north into Pennsylvania, he had to deal with the enemy in his rear to open the Valley as a supply route and, if needed, route of retreat back to Virginia.
On the evening of September 9, 1862, staff officers and couriers emanated from Lee's headquarters outside of Frederick. The riders delivered multiple copies of Special Orders No. 191 to Lee's subordinates. The orders outlined the division of the Army of Northern Virginia into multiple pieces, three of which, led by Stonewall Jackson, Lafayette McLaws, and John Walker, would take different routes to intercept, destroy, or capture the enemy garrisons at Martinsburg and Harpers Ferry. When the orders went into effect the next day, Lee anticipated that these three wings would wrap up the operations in the Valley quickly--perhaps as early as September 12--before the army reunited and continued on its trek north.
